Electrical resistance



G. H. DORGELOH.

ELECTRICAL RESISTANCE.

APPLICATION FILED AUG. 28, 1919.

Patented Nov. 30, 1920.

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IEORGE H. DORGELOH, OF BLOOMFIELD. NEW JERSEY, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL RESISTANCE.

Specification of Letters Patent.

Patented Nov. 30, 1920.

T 0 all whom it may concern:

Be it known that I, Gaoner. H. DORGELOH, a citizen of the United States, residing at Bloomfield, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Electrical Resistances, of which the following is a specification.

My invention relates to electrical resistance units of the type in which the resistance element is in the form of a continuous conductor, and has for its objectthe im rovement in devices of this character.

ore specifically, my invention relates to a form of resistance unit comprised of a plurality of units or grids. Ordinarily, these grids have been made as separate elements cast into proper shape and assembled in a bank to form the resistance unit. In these cases, the electrical connections between the separate grids forming the unit are made by contact pressure between the successive grids which are assembled on rods and pressed together. In my present invention, as stated, the unit is made from a continuous element formed into successive grids and one of the objects of my invention is to make such a connection to the resistance elementthat it. will not be subjected to vibration and will be rigid and rugged. In resistance units of this character, the circuit connection has been made at the ends of the terminal loops of the grid. In such an arrangement, the weight of the conductor bore upon the particular convolution to which it was secured and the conductor was subjected to the vibrations of the grid. It was found that the conductor sooner or later became brittle near the point of connection and broke. This was particularly true when the grid was subjected to much jarring, such as on electric railway cars, where these t pes of resistance units are largely used. oreover there is a tendency to weaken the grid, and the grid is subjected to injury by reason of any strain of the conductor.

In order to overcome these difiiculties and at the same time provide a compact and efficient terminal connect-ion easily ca able of adjustment to various resistances, provide a. rugged terminal for the circuit conductor which is supported by the mam supporting member of the resistance element.

This terminal is not supported by a convolution or any palt of the grid and therefore is not subjected to its vibrations. The connection between said terminal and an intermediate point on the resistance element between the points of support for the resistance element is made by means of a light flexible conductor, or pigtail, secured at one end to said terminal and at its opposite end to the end of one of the convolntions of the grid. Thus, the circuit conductor is rigidly supported and better able to withstand the general vibration to which the whole resistance may be subjected and the grid is not subjected to the weight of the conductor or any unusual strain to which said conductor may be sumbitted. Further objects and purposes of my invention will appear in the course of the following specification in which I have shown my invention embodied in concrete form for the purpose of illustration.

In the accompanying drawings illustrating my invention, Figure 1 is a side eleva tion of a grid resistance embodying my invention, Fig. 2 is a longitudinal section partly in elevation and Fig. 3 isa detail of Fig. 1 showing .the terminal connection.

Referring to the drawings, the resistance element 1 comprises a continuous series of parallel units 2 each formed into a number of regular convolutions or sinuous windings as shown in Fig. 1. The resistance 1 is supported at a plurality of points by the two rods 3, which are covered with an insulating material 4 and extend through a supporting frame 10. Each unit 2 intermediate the end units is bent over a rod 3 at each end of the unit and twisted back to again bend over the same rod 3 to form a loop 5 through which the unit connects with the next adjacent unit. Thus, starting at one end of the element, one end of the first unit is bent part wa around the rod 3, the other end of this unit is bent part way around the rod 3 for supporting the other end of the unit, then this end of the unit is bent back so as to form a loop 5 and again bent around the latter supporting rod, the loop 5 being considered as the connection between the first and the second units, and so on through the sinuous conductor. The several units 2 are separated from each other by insulated washers 6, mounted on the rods 3, as shown in Fig. 2. The resistance element is made secure b the tightening of nuts 7 at the ends of t e rods 3. A. rugged terminal 8, shown in Fig. 3, supports the circuit conductor 9 and is in electrical contact therewith. it will be seen from the drawing that the upper portion of the terminal 8 is provided with a curved portion 11 to fit the conductor 5) and extends upwardly from said curved portion a short distance where it is bent over forming a clamp 12 around the conductor 9, which clamp is tightened by means of a bolt .13. At its lower end, the terminal 8 is provided with an opening-14 forming a saddle to fit over the rods 3. The terminal is also insulated from the resistance element by washers l5), and is made secure by tightening the nuts 7.

The conductor 9 is connected to the resistance element 1 by means of a light flexible conductor, or pigtail, 15, which is secured at one end to a cleat 16, and in electrical contact therewith, said cleat being secured to the terminal 8 by bolt 13. as shown in Fig. 2. At its opposite end said conductor 15 is secured by a cleat 17 to the end of one of the convolutions of said resistance element 1, at 18, and in electrical contact therewith. The connection to the resistance element is thus at an intermediate point on the resistor between the points of support for the resistor. The circuit from conductor 9 to the resistance element is through the terminal 8, cleat 16, conductor 15 and cleat 17. It is of course understood that two terminals may be used if desired to complete the circuit, these terminals being mounted on the rods 3 to permit the respective conductors 15 thereof to be secured to the proper convolution to give the desired resistance.

\Vhile I have described my invention as embodied in concrete form and as operating in a specific manner in accordance with the provisions of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art Without departing from the spirit of my invention the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A resistance unit for electric circuits, comprising a continuous conductor formed into a plurality of grids, a support for sup porting said grids at a plurality of points, a terminal for connectin r with the electric circuit mounted on sai support and an electrical connection between the terminal and a point on the conductor between its points of support and remote from the support.

2. A resistance unit for electric circuits, comprising a continuous conductor formed into a plurality of grids, a support for supporting said grids at a plurality of points, a terminal for connecting with the electric circuit mounted on said support and a flexible conductor connecting said terminal to one of said grids between the points of sup port for the grid.

3. A resistance unit for electric circuits, comprising a series of parallel sinuous units, a support for supporting said units at a plurality of points. a terminal for connecting with the electric circuit mounted on said support and an electrical connection between the terminal and one of said units between the points of support for the unit.

4. A resistance unit for electric circuits, comprising a continuous conductor formed into a series of parallel 'convolute units, a support for supporting said units at a plurality of points, a terminal for connecting with the electric circuit mounted on said support, and a flexible conductor connectin r said terminal to the end of a convolution and between the points of support of one of said 

